Lambda Integration vs. Lambda Proxy: Pros and Cons

Question

What do you think are the Pros and Cons of using Lambda integration with and without the proxy feature in AWS API Gateway (and more specifically, when using the Serverless f

Answer 1

It looks like AWS recommends choosing Lambda Proxy Integration for new API development.

Note

The Lambda custom integration, formerly known as the Lambda integration, is a legacy technology. We recommend that you use the Lambda proxy integration for any new API. For more information, see Build an API Gateway API with Lambda Proxy Integration

I understand that it's a lot "quicker" (in the short term) to spin up an API endpoint and lambda integration using proxy integration rather than the custom integration, but I'm surprised that it's the recommendation for all API / Lambda development going forward:

• I pictured API Gateway as being responsible for handling the "HTTP details". Using Proxy Integration forces (at least a subset of) that responsibility onto the Lambda function. (i.e. knowing how to interpret and decide on HTTP headers, query parameters, status codes, etc.)
• In doing that, I feel that it muddies the responsibility of the backing Lambda function -- Lambda now needs to both handle whatever "business" logic it's being called to do, and also handle interpreting the incoming HTTP values and decide on the outgoing HTTP response values.
• Granted, you could implement an additional Lambda function layer to abstract away the HTTP details, but isn't that what API Gateway is supposed to do?
• It reduces the ability to re-use any given Lambda function in a context other than servicing HTTP requests, unless non-HTTP clients format the request as if it were an HTTP request.